In a dioecious flowering plant, which types of pollination are prevented?

Autogamy and geitonogamy

The correct answer is Option (3)-Autogamy and geitonogamy

In dioecious flowering plants, individual plants have either male or female reproductive organs, but not both. This means that self-pollination within the same flower (autogamy) or between flowers on the same plant (geitonogamy) is prevented.

• Autogamy (self-pollination) cannot occur because male and female flowers are on separate plants.
• Geitonogamy (pollination between different flowers on the same plant) is also not possible since a single plant only has male or female flowers, not both.

However, xenogamy (pollination between different plants) is not prevented, as it is essential for dioecious plants to reproduce, relying on cross-pollination between separate male and female plants.